title: Do toxic ions induce hormesis in plants?
abstract: The concept of hormesis in plants is critically reviewed, taking growth stimulation by low concentrations of toxic trace elements as a reference. The importance of both non-adaptive and adaptive mechanisms underlying ion-induced hormetic growth responses is highlighted. The activation of defense mechanisms by metal ions and pathogenic elicitors and the cross talk between the signals induced by metal ions and biotic stressors are considered. The production of reactive oxygen species and, consequently, the induction of stress-induced antioxidants, are key mechanisms in metal ion-induced hormesis in plants. It is concluded that in the current scientific literature, hormesis is used as an "umbrella" term that includes a wide range of different mechanisms. It is recommended that the term hormesis be used in plant toxicology as a descriptive term for the stimulated phase in growth response curves that is induced by low concentrations of toxic metal ions without evidence of the underlying mechanisms. If the mechanisms underlying the stimulated growth phase have been identified, specific terms, such as amelioration, defense gene activation, priming or acclimation, should be used.
authors.affiliation: Lab. Fisiología Vegetal, Facultad Biociencias, Universidad Autónoma de Barcelona, E-08193 Bellaterra, Spain. Electronic address: charlotte.poschenrieder@uab.es.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Poschenrieder
authors.forename: Catalina
authors.initials: C
authors.lastname: Cabot
authors.forename: Soledad
authors.initials: S
authors.lastname: Martos
authors.forename: Berta
authors.initials: B
authors.lastname: Gallego
authors.forename: Juan
authors.initials: J
authors.lastname: Barceló
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D059165:Hormesis; D007477:Ions / Q000633:toxicity; D008670:Metals / Q000633:toxicity*; D063245:Plant Development / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013312:Stress, Physiological; D014131:Trace Elements / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D007477:Ions; D008670:Metals; D017382:Reactive Oxygen Species; D014131:Trace Elements
keywords: Acclimation; Antioxidant; Defense; Hormesis; Metal ion; Toxicity